Active Roll Support Control Using Rear Axle Grip Reserve
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Solution Overview
Problem
Existing active roll support systems for motor vehicles rely on inaccurate and delayed oversteering or understeering signals for feedback, which are insufficient for varying road surface friction coefficients, tire types, and vehicle configurations, limiting their effectiveness in regulating roll moment distribution during cornering.
Innovation Solution
A method that regulates roll moment distribution based on the actual grip reserve of the rear axle relative to the front axle, using wheel loads, slip angles, and other variables to calculate grip potential and adjust roll moment distribution, with control deviations calculated from target grip reserves and feedback variables like driving speed and lateral acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oversteering or understeering signals are used for feedback in active roll support systems, then the system can provide roll moment distribution, but the feedback is inaccurate and delayed, limiting effectiveness
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the actual grip reserve of the rear axle relative to the front axle using wheel load sensors and grip potential calculations. This real-time feedback replaces the inaccurate and delayed oversteering/understeering signals, enabling the control system to dynamically adjust roll moment distribution based on current traction conditions at each wheel, thereby improving both accuracy and responsiveness
Solution Approach 2:
The patent replaces the mechanical sensing approach (oversteering/understeering signals from vehicle dynamics) with an electronic calculation system that computes grip potential for each wheel based on measured wheel loads, slip angles, and friction coefficients. This substitution enables more precise and immediate detection of grip conditions without the delays inherent in mechanical signal transmission
2Measurement precision
If roll moment distribution is regulated based on grip reserve calculations using multiple variables, then regulation accuracy improves, but system complexity increases
Solution Approach 1:
The patent segments the grip potential calculation into individual wheel-level computations, where each wheel's grip potential is calculated separately based on its specific wheel load, slip angle, and friction conditions. This segmentation allows the system to handle complex multi-variable calculations in a modular fashion, improving measurement precision while managing system complexity through structured computation
Solution Approach 2:
The patent employs a universal control algorithm that regulates roll moment distribution across all axles using the same grip reserve calculation methodology. This multi-functional approach applies the same precise calculation logic to front and rear axles, enabling accurate regulation throughout the vehicle without requiring separate complex control systems for each axle
Data Source
AI summary
A method for operating an active roll support system of a motor vehicle, in which a roll moment distribution is regulated below a sideslip angle threshold on the basis of an actual grip reserve of a rear axle relative to a front axle of the motor vehicle. A wheel load is acquired for each of the wheels of the front axle and for each of the wheels of the rear axle and the acquired wheel loads are used as feedback variables in a control loop for regulating the roll moment distribution to calculate the actual grip reserve of the rear axle and compare it with a target grip reserve of the rear axle and from this determine a control deviation for adapting the roll moment distribution.